The Stovebolt Site Forums The Shop Area The Electrical Bay Troubleshooting generator and rough idle

Hi everyone, still working on my 59 Apache. Got it to it's first car show and back without any issues buuut then I took it out the next day. Made it a ways down the road just fine but idle started getting real slow and rough and stopped on me twice. Took it back out about a half hour later, made it about a mile and engine dropped idle, lost all acceleration, then died and would not restart. Waited 20 minutes, started up, drove it another mile and same thing. First thing I checked was timing, then carb. All good. Doing several tests I found that when the engine first starts the generator puts out the needed 14v. After a few minutes it gets tired, drops down to 10-12. This is when the rough idle and power loss start. I pull out choke to get rpms back up but generator output remains low. Battery is at about a full charge though so not sure why idle would be affected as I thought the battery should run the ignition when generator is slacking. Checked power to the coil. When generator is putting out needed voltage coil is getting typical 9v. Here's the weird thing though. When generator starts dropping volts and rough idle starts, power to the coil shoots up to 11.5 v. Don't know why this happens or if it would cause the rough idle and power loss. Obviously I need the gerlnerator rebuilt, but trying to figure out if I need to replace voltage regulator and or ignition coil too. Any thoughts welcome!

It may not be the generator at fault, first thing to do is make sure all of the connections are clean and tight, then clean the contacts in the voltage regulator. Use clean white paper to clean the contacts, no abrasive sandpaper.

Thanks for the quick response! I have a new voltage regulator on standby if I need it, so I might just swap that out and see if that fixes it. It seems pretty clear the generator isn't putting out what it should, and that's measured from the terminals so I know it's not just a connection issue, but would that in itself be enough to mess with the idle if the battery, voltage regulator, and coil are all functioning properly? I would think a fully charged battery would be able to pick up the slack from the generator for at least a little bit right?

Mario,

I know we are talking in the "electrical bay", but your originally described conditions of power loss and stalling sounds more like a possible fuel starvation/restriction problem. Possibly rust/debris floating around in the tank till suctions draws it to cause a feed blockage (or in an inline filter possibly). I think the ability of the engine to restart after sitting a while may indicate that if you have a debris blockage, it could be settling out to allow fuel to flow until the debris is stirred up again and blocks off the flow again. A lack of fuel would account for the reduced idle speed/power loss and eventual stall out and the reductions in generator output could be related to just the reduced engine RPM.

Just a little out-loud thinking and maybe worth you checking out to eliminate this as a possible problems source.

If replacing your regulator doesn't resolve the issue, check your fuel circuit.

Dan

Dan, are you a wizard? Clogged filter, runs like new. Well almost. Generator is now only outputting 9-10v, but I'll put the battery on charge and deal with that when I feel like it. There's a local guy who rebuilds them pretty cheap, or maybe I'll take a swing at it myself. Thanks again everyone!

What was clogging the filter? Didn't the truck just get restored?

Not exactly. My grandpa started restoring it years before he passed, but he could never actually get it going long enough to drive it home. I'm pretty sure somewhere in the last 10 years he put that Gas tank on, but it did sit for a few years before I got a hold of it in any case. I've been restoring it over the last 6 months (aka just trying to fix whatever breaks as I get it on the road), so I've only been putting a few gallons in the tank at a time as I got the ignition system working, then the fuel system, then engine, (then had a mishap where I ruined the stock steering knuckle, that was a nightmare) and so on. This week was the first time I've really filled the tank to full, and I topped it off with a bottle of gumout for good measure- didn't even think to check the filter off of the tank to see how it was handling the sludge that was getting broken up

Could you tell what was clogging the line? If rust, you probably need a new tank. Sitting around empty encourages rust. When you figure it out or put a new tank in it, keep it filled to the top.

With a full tank of fuel and GumOut in it, you need to change the filter/s until the system is clean. I would add at least one more filter if the current set-up has only one.

It's got a paper one before the carb as well, but yeah I should probably change that one soon too. The sludge in the old filter had a distinct rust color to it, so I'm going to guess that's what it was

I have a modern steel cased filter in front of the fuel pump and the sediment/paper filter in front of the carburetor, I still get extremely fine sediment in the float bowl of the carburetor. I have to clean that occasionally. You may want to disassemble the carburetor and check it.

Yes, tank is rusting inside.

Needs sealing or the rust will continue.

I clean a rusty fuel tank by strapping it to a rear wheel on my tractor, with a strong solution of laundry detergent and a scoop of pea gravel inside- - - -then I go out and bush hog a pasture. The rust just magically disappears!
Jerry

Three cheers Mario!!!

When you can, get the tank and rest of fuel system thoroughly checked and address any issue.

Glad it was a helpful thought!

Dan

I see. So what I'm hearing is I need to clean the tank and then seal it before I keep driving? I had hoped the gumout and fuel filters would be enough to clean everything up and keep anything out, but I'd rather be safe than sorry, especially if sorry means wearing out an antique engine. Jerry the tractor idea sounds pretty great, and I could have some fun with it. Do you fill the tank full or just like half? And is there maybe a chemical solution that involves leaving the tank in place?

Wait Guitplayer are you saying I can just seal the tank as is?

I fill the tank about halfway or a little more with the water/detergent solution and add enough gravel to get a good bit of agitation as the wheel turns. Seal up all the holes well so the cleaner stays inside and doesn't leak away. There's really no need for a sealer afterwards- - - -the tank gets cleaned right down to bare metal, sort of like sandblasting, only with wet media.
Jerry

Before I knew about Jerry's reverse rock tumbling method (polishing the inside of the tumbler instead of the rocks) I used one of the sloshing compounds offered by a lot of the restoration houses.

My '56 Cadillac tank was done over 20 years ago and has had no problems with delamination or leaking.

The '64 Galaxie was done sometime in the 1990s and held up very well for 20+ years until a couple years ago when it started leaking.

In both cases new tanks were not being made for these cars so repairing the original was the best solution. The Galaxie had pinholes so a sealer was absolutely necessary.

The Cadillac was rusty but not leaking. The sealing system took care of the rust and it's still on the car today. I'd have used Jerry's method if I'd known about it since my dad had an 8N tractor at the time.

Check into the cost of a new tank vs sealing and or rock tumbling. If you don't have a tractor, rig up some sort of rotisserie to do the same thing.

A good cleaning may result in some pinhole leaks like my 37
I took the time to use the POR15 kit. Still good after 25 years and I've never changed filters since.....but plan to soon!!!!